Semi-active radar homing (SARH) is a common type of missile guidance system, perhaps the most common type for longer-range air-to-air and surface-to-air missile systems. The name refers to the fact that the missile itself is only a passive detector of a radar signal—provided by an external ("offboard") source—as it reflects off the target. Semi-active missile systems use bistatic continuous-wave radar.

The RIM-161 Standard Missile 3 (SM-3) is a ship-based surface-to-air missile used by the United States Navy to intercept short- and intermediate-range ballistic missiles as a part of Aegis Ballistic Missile Defense System. Although primarily designed as an anti-ballistic missile, the SM-3 has also been employed in an anti-satellite capacity against a satellite at the lower end of low Earth orbit. The SM-3 is primarily used and tested by the United States Navy and also operated by the Japan Maritime Self-Defense Force.